1. Field of the Invention
The present invention relates generally to scenting compositions formulated for spray application on air scenting devices and to the devices having such scented compositions applied thereon as well as to processes for application of the scenting compositions to air scenting devices. More particularly, it relates to scented or fragranced compositions for spray application on devices such as air filters, for example, in mechanical forced air heating, ventilating and air conditioning (“HVAC”) systems to provide long lasting freshening or scenting of air flowing through the devices with minimal blockage of air permeating therethrough.
2. Description of Related Art
The use of air scenting or freshening devices has long been known for use in releasing fragrances of various types in ambient air. Such devices have been used successfully for purposes of scenting and/or freshening air in confined spaces, particularly to mask odors such as may occur in the form of cooking odors, pet odors, tobacco smoke and the like. Furthermore, such devices have been adapted for use in mechanical HVAC systems wherein air is circulated within an interior space.
The general concept of providing a sustained release mechanism for air freshening the home is the subject of numerous patents and consumer products. Leading commercially available products in this category have common design elements which include 1) a sponge like/cardboard substrate which is mounted to the filter, 2) a fragranced gel/wax mixture which is coated/beaded onto the sponge or cardboard, 3) a plastic/metal mount which fixes the sponge or cardboard to the filter, 4) a foil wrap/packette outer package for insuring that the product will not loose fragrance after manufacturing and prior to purchase by the ultimate consumer.
These prior art air scenting/freshening devices, systems and compositions are described in the following exemplary U.S. Patents. For example, U.S. Pat. No. 2,871,526 describes an air odor control system including an odor control composition positioned in a porous container for dispensing vapors to control odors. U.S. Pat. No. 4,065,262 describes an air freshening apparatus utilizing an air filter element having a plurality of containers positioned in the air filter for holding an air freshening composition. U.S. Pat. No. 4,102,656 describes an odor conditioning apparatus including a filter element positioned to be dipped into a reservoir containing a liquid which will wick into the filter to be vaporized into the environment.
U.S. Pat. No. 4,118,226 describes an air freshening device wherein a solid aromatic medium is positioned in a perforated case which, in turn, is placed in a ventilating system. U.S. Pat. No. 4,604,114 similarly describes placing large solid rods of fragrant scented material in an air circulation system. Additionally, U.S. Pat. No. 4,563,333 describes a deodorizing fitting for an air filter in which a rectangular envelope of perforated cardboard with a deodorizing insert therein is adhered to a corner of the filter; U.S. Pat. No. 4,523,870 describes an aroma dispensing cartridge placed in front of an air vent and U.S. Pat. No. 4,735,358 describes a system wherein fragrant material is placed on a tape from which the material vaporizes when the tape is run across a tape head by drive means.
It should be noted that many of the above described prior art devices disadvantageously interfere with the normal flow of air through the HVAC system and cause blockage of air flow through air filters to which they are attached of about 10% or more of the total air engaging or impinging on the filter. Further, none of the aforesaid devices can be readily employed in a pre-existing filter systems. Rather, specifically designed frames or casings must be used to hold the fragrant structures.
In recent times a scented air freshening device has been developed which offers improved convenience and reduced air flow restriction when used with a standard air filter of a type found in conventional force air ventilation systems. This device is described in U.S. Pat. Nos. 5,547,636 and 5,698,166. As shown therein, a conventional air filter of the type including a porous mesh supported in a paperboard frame is fitted on its front or outwardly facing surface (i.e., the upstream surface of the filter which, when installed, faces the fan or other source of air flow in an HVAC system) with a portion of a flat porous substrate, such as an air permeable sponge material. The substrate is provided with a solution of fragrant material which may include a polymer and volatile solvent. When installed in an HVAC system, the solvent is allowed to evaporate leaving a dried fragrant polymeric residue on the substrate from which a fragrant scent is slowly released. Conveniently, the substrate may be attached to the front or outward facing surface of the air filter by the use of a simple barbed connector which pierces both the substrate and filter medium and holds the substrate in place. This device has proved to be most advantageous to homeowners who wish to use their HVAC systems to introduce and circulate a desirable fragrance throughout their homes. The device is essentially usable with any conventional furnace air filter and is highly cost effective in manufacture and sale.
Other generally similar air scenting/freshening devices adapted for installation on the front or outward facing surface of a conventional air filter in an HVAC system are described in U.S. Pat. No. 5,087,273 wherein the device comprises an air permeable envelope containing aromatic beads which is positioned on the upstream or air flow facing side of the filter to provide a fragrant scent to the air circulated through the system and in U.S. Pat. No. 6,117,218 wherein the device comprises a scenting device for attachment to the upstream face of an air filter comprising a sheet formed from a material which is substantially impervious to air having a viscous liquid, such as a gel, containing a fragrance applied thereto and including openings therein through which scented air flows into and through the filter. However, each of these devices suffers from the same problems as noted above relative to the devices described in U.S. Pat. Nos. 5,547,636 and 5,698,166.
Although the above-described substrate devices have provided certain improvements over the prior art, they are not without disadvantages. Primarily, in order to use the devices effectively, the substrates must be attached to the upstream front or outward facing surface of a ventilating system air filter. Attachment of these prior art substrates to the upstream surface of the filter has been necessary in order to eliminate the risk that would be presented if the substrate were to be affixed to the downstream surface of the filter. That is, if these substrates were positioned on the downstream surface, the substrate itself or disintegrated portions of the substrate could become dislodged from the downstream surface and could cause damage to the mechanical components of the HVAC system during operation. Also, the dislodged material can be directly disseminated into the environment with the HVAC air flow exiting from the filter on the downstream side thereof over extended periods of time of use.
However, when the substrates of the prior art are attached to the outward facing surface of the air filter to avoid this possible contamination problem, the substrates are naturally exposed to unfiltered particulate matter entrained in the ambient air entering the filter which has a tendency to cause premature blockage or clogging of the substrate and to, thereby, diminish its effectiveness of the device from releasing scented fragrance through the filter over time.
In our co-pending U.S. patent application Ser. No. 09/994,231, a further improved air freshening system is disclosed employing an air freshening composition comprising a thermoplastic, semi-permeable polymeric gel having a fragrance material incorporated therein. The composition is formulated for application to an air filter such as employed in an HVAC system to provide an air freshening scent to air passing through the filter by dispersing scented, volatile components into the air over a predetermined period of time. These gel composition have been found to be advantageous in overcoming many of the problems encountered with the prior art the substrates which must be attached to the upstream front or outward facing surface of a ventilating system filter. However, it has been recognized that the provision of a suitable spray on scenting composition that would provide long lasting air freshening or scenting to air passing through the filter without causing significant blockage of the filter surface would be extremely beneficial and could provide an even better and more cost efficient solution to the problems presented by the prior art.
In this regard, U.S. Pat. No. 4,159,672 describes apparatus for automatically introducing a scent into a forced air temperature changing system by pumping a scent containing fluid through tubes positioned adjacent to an air filter and spraying the pumped fluid onto the filter so that air flowing through the filter picks up the scent and brings the scent to the desired area. However, this patent provides no description of the formulation of the scent containing fluid nor does it provide any solution to the air flow blockage problem that would be presented by spraying such compositions onto a filter from the tubes. Still further, this patent does not suggest or teach the formulation of the scent containing fluid so as to provide long lasting freshening or scenting of air flowing through the filter.
Providing long lasting freshening or scenting or air in an HVAC system has been a continuing problem with prior art air freshening or scenting devices arising from the volatile nature of liquid fragrances. Fragrances for scenting air typically are liquid oils. Such fragrant oils are mixtures of many different chemicals. Most of the chemicals mixed into a fragrance oil are liquids, but some components are solid. A solvent is used to dissolve the components together to form a homogenous fragrant liquid oil. The components have relatively high vapor pressures. Thus, the fragrant liquids evaporate readily giving rise to fragrance “flash-off” problems during the manufacture of the devices. Fragrant liquid oils, therefore, are not satisfactory for use in forced air ventilation systems carrying air at significant velocities. The present invention accordingly, addresses the conflicting problems associated with the deodorizing and scenting of air in forced air ventilation systems of entraining an effective amount of scent into the air while achieving sufficient longevity of scenting activity.
Accordingly, there exists a continuing need for a scented air freshening composition which may be used in a HVAC heating, ventilating, and cooling system for deodorizing and freshening air distributed in the system and will cause minimal interference with the circulation of air through the system while providing sufficient scenting of the circulating air for a relatively extended predetermined period of time.
In view of the foregoing, it is a general object of the present invention to further improve over the prior art by providing a scented or fragranced composition for spray application on air filters used in air scenting devices and to devices and processes for scenting air circulated in an HVAC system or the like utilizing such spray applied scented or fragranced compositions.
Another object is to provide compositions for spray application on air filters used in a device and process for freshening or scenting air in an HVAC system or the like wherein the sprayed composition provides an air permeable coating layer on the surface of the air filter with the sprayed coating layer containing a volatile component which will evaporate over a relatively extended predetermined period of time to impart a desired fragrance to the surrounding environment.
A further object is to provide a device for freshening or scenting air in an HVAC system wherein a fragrant coating layer is sprayed onto a filter surface to freshen or scent the air and wherein the coating layer will not cause the filter to become blocked by particulate matter contained within ambient circulated air over a relatively extended period of time.
A still further object is to provide a composition for freshening or scenting air which is usable in a standard or conventional ventilating system air filter device and can conveniently be applied by spraying either on the front or outward facing surface of the air filter or, more preferably, on the reverse or inward facing surface of the filter so that only filtered air will impinge thereon.
Yet another object is to provide a device for scenting or freshening air which is convenient for application and which is highly cost-effective and efficient in use.
These and other objects will become apparent hereinafter to those skilled in the art.